This is the mail archive of the
libc-alpha@sourceware.org
mailing list for the glibc project.
Re: [PATCH] x86-64: Add sinf with FMA
On Tue, 5 Dec 2017, Adhemerval Zanella wrote:
> +#else
> + res = __builtin_floor (d);
> +#endif
> return res;
> }
> ---
>
> As least for GCC7 compiler will expand to an inline version even for generic
> tune option. However the code that actually calls __floor is not showing on
Which, as per discussions on gcc-patches in August, may not be a good idea
with current GCC, because it means that your code built for generic SSE2
is now slower on an SSE4.1 processor than it would have been if it had
called the __floor IFUNC. (That issue could be avoided by adding an
SSE4.1 IFUNC of sinf, of course. I think we should aim to use floor etc.
directly anyway - in cases where we can't avoid floor and just convert
directly to integer - and address any such pessimizations in GCC rather
than working around them in glibc.)
--
Joseph S. Myers
joseph@codesourcery.com